//------------------------------------------------------------
// Game Framework
// Copyright © 2013-2021 Jiang Yin. All rights reserved.
// Homepage: https://gameframework.cn/
// Feedback: mailto:ellan@gameframework.cn
//------------------------------------------------------------

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

/// <summary>
/// 事件组件。
/// </summary>
[DisallowMultipleComponent]
[AddComponentMenu("Game Framework/Event")]
public sealed class EventComponent : MonoBehaviour
{
    private static EventComponent m_Instance;
    private IEventManager m_EventManager = null;

    public static EventComponent Instance
    {
        get
        {
            if (m_Instance == null)
            {
                m_Instance = FindObjectOfType<EventComponent>();
                if (m_Instance == null)
                {
                    GameObject go = new GameObject("EventComponent");
                    m_Instance = go.AddComponent<EventComponent>();
                    DontDestroyOnLoad(go);
                }
            }
            return m_Instance;
        }
    }

    /// <summary>
    /// 获取事件处理函数的数量。
    /// </summary>
    public int EventHandlerCount
    {
        get
        {
            return m_EventManager.EventHandlerCount;
        }
    }

    /// <summary>
    /// 获取事件数量。
    /// </summary>
    public int EventCount
    {
        get
        {
            return m_EventManager.EventCount;
        }
    }
    public IEnumerable<EventHandler<GameEventArgs>> EventHandlers() => m_EventManager.EventHandlers();
    public IEnumerable<object> Events() => m_EventManager.Events();

    /// <summary>
    /// 游戏框架组件初始化。
    /// </summary>
    private void Awake()
    {
        if (m_Instance == null)
        {
            m_Instance = this;
            DontDestroyOnLoad(gameObject);
        }
        else if (m_Instance != this)
        {
            Destroy(gameObject);
            return;
        }

        m_EventManager = new EventManager();
    }

    private void Update()
    {
        if (m_EventManager is EventManager eventManager)
        {
            eventManager.Update(Time.deltaTime, Time.unscaledDeltaTime);
        }
    }

    private void OnDestroy()
    {
        if (m_EventManager is EventManager eventManager)
        {
            eventManager.Shutdown();
        }
        if (m_Instance == this)
        {
            m_Instance = null;
        }
    }

    /// <summary>
    /// 获取事件处理函数的数量。
    /// </summary>
    /// <param name="id">事件类型编号。</param>
    /// <returns>事件处理函数的数量。</returns>
    public int Count(int id)
    {
        return m_EventManager.Count(id);
    }

    /// <summary>
    /// 检查是否存在事件处理函数。
    /// </summary>
    /// <param name="id">事件类型编号。</param>
    /// <param name="handler">要检查的事件处理函数。</param>
    /// <returns>是否存在事件处理函数。</returns>
    public bool Check(int id, EventHandler<GameEventArgs> handler)
    {
        return m_EventManager.Check(id, handler);
    }

    /// <summary>
    /// 订阅事件处理回调函数。
    /// </summary>
    /// <param name="id">事件类型编号。</param>
    /// <param name="handler">要订阅的事件处理回调函数。</param>
    public void Subscribe(int id, EventHandler<GameEventArgs> handler)
    {
        m_EventManager.Subscribe(id, handler);
    }

    /// <summary>
    /// 取消订阅事件处理回调函数。
    /// </summary>
    /// <param name="id">事件类型编号。</param>
    /// <param name="handler">要取消订阅的事件处理回调函数。</param>
    public void Unsubscribe(int id, EventHandler<GameEventArgs> handler)
    {
        m_EventManager.Unsubscribe(id, handler);
    }

    /// <summary>
    /// 设置默认事件处理函数。
    /// </summary>
    /// <param name="handler">要设置的默认事件处理函数。</param>
    public void SetDefaultHandler(EventHandler<GameEventArgs> handler)
    {
        m_EventManager.SetDefaultHandler(handler);
    }

    /// <summary>
    /// 抛出事件，这个操作是线程安全的，即使不在主线程中抛出，也可保证在主线程中回调事件处理函数，但事件会在抛出后的下一帧分发。
    /// </summary>
    /// <param name="sender">事件发送者。</param>
    /// <param name="e">事件内容。</param>
    public void Fire(object sender, GameEventArgs e)
    {
        m_EventManager.Fire(sender, e);
    }

    /// <summary>
    /// 抛出事件立即模式，这个操作不是线程安全的，事件会立刻分发。
    /// </summary>
    /// <param name="sender">事件发送者。</param>
    /// <param name="e">事件内容。</param>
    public void FireNow(object sender, GameEventArgs e)
    {
        m_EventManager.FireNow(sender, e);
    }

    public void AddOnShutdownEvt(Action action)
    {
        m_EventManager.AddOnShutdownEvt(action);
    }
}

